So, you want a new cat. But you already have a cat that considers your entire home and garden its own territory. How are you going to make sure that the two get on?

Unfortunately it is impossible to be sure that a new cat will get on with your existing feline friend, but there are a few things you can do to help the whole process along a little more smoothly.

As with everything relating to animals, all of the following should be taken with a pinch of salt! It is based on suggestions from many people and the personal experience of introducing four very different cats to one another. Everyone's experience with cats is different and you should learn to trust your own instincts.

Cat Character

If your existing cat is a grumpy, angry moggie who will spit and growl at every living creature that comes near your house, you may have to accept that it will never get on with a newcomer. And some cats just hate other cats for company.

But assuming your cat is at least vaguely tolerant of others, your choice of new cat can help. Choosing a kitten is a good start, as small young balls of fluff aren't very threatening, and are more likely to be accepted, though a kitten may not be entirely suitable if your current cat is elderly. Two middle aged cats can get on perfectly well.

Indeed, there are some advantages to an older cat. A kitten's character is not yet apparent, whereas an older cat (which you should get from a rescue home - there's no point paying for a cat when there are thousands desperate for a home!) will have a developed character to guide your choice of companion for your existing cat.

Preparations

Set up a room for your new cat. Your spare bedroom is ideal. Get a litter tray, food and water dishes and somewhere warm to sleep.

The first day

Bring in the new cat while your old cat is on the prowl outside or shut in the kitchen - with some fresh food or treats! Keep your new cat in the spare room with the door shut.

Although you will be tempted to play and pet your new feline friend, do not neglect your current cat's routine. Continue to give it the same attention, time, treats and hugs as always, or it will come to resent the new cat very quickly.

The first week

Keep your cats separate for the first few days and allow them to acclimatize to each others' smell. You can swap their blankets or food bowls to help achieve this, and try feeding your new cat by the door whilst feeding your existing cat treats on the other side.

If, after a few days, your existing cat isn't snarling at the door, you can consider moving towards the introduction. If they still spit a the smell of each other, you may want to leave it a few more days.

First, however, you should shut your existing cat into a room or ensure he's outside so you can give your new cat the run of the house. This will give him or her the opportunity to explore and feel safe - this first meeting will probably be scary for one or both cats, so they need to know where they can run and hide!

The first meeting

Try to make this a relaxed introduction. Do not pick them up and force them together. Choose a time when they have both recently eaten and let them find each other. If they do not immediately lunge for each other, arch backs or start snarling, this is a very good sign! You can now let them spend supervised time together.

If, however, they aren't very keen on each other, return them to separate rooms and pet them both to reassure them.

Do not shout at them! Shouting at them if they fight is not a good way to endear them to one another and will make it more difficult when you reintroduce them tomorrow or the day after.

The first months

Once they start to get along - or at least tolerate each other - you can let them spend more time together, though for the first few weeks or even months you may want to keep your new cat in your spare room when you are out, especially if they are wary of each other.

You should move the new cat's litter tray and food out of the spare room and into the regular place once they reach a stage where you can leave them alone without coming back to signs of a fight, or to a frightened cat hiding under the couch.

The future

Your cats may never be best buddies; having cats which simply accept each other should be considered a success. In extreme cases you may have to return your new cat to the shelter, or consult a professional animal psychologist - yes they do really exist!

Some cats will never do more than studiously ignore the other, while others will be playing and sleeping together after just a few weeks.

Good luck!